Phylogeny and taxonomic revision of Thelonectria discophora (Ascomycota, Hypocreales, Nectriaceae) species complex

Specimens regarded as Thelonectria discophora (Thelonectria, Nectriaceae, Hypocreales) constitute a conspicuous group of saprobic fungi on decaying plant material, characterized by red perithecia each with a broad mammiform (nipple-like) apex. The asexual state is characterized by a cylindrocarpon-like morphology, with 3–5 septate macroconidia, unicellular microconidia and chlamydospores that are rarely produced in culture. In the past, T. discophora was regarded as one species with a wide geographic distribution. However, a recent study rejected the monophyly and cosmopolitan distribution of this species, and showed the existence of at least 16 cryptic species distributed in three main groups. By combining the results of phylogenetic analyses of six nuclear loci and morphological studies, we revised the taxonomy of the T. discophora species complex, resulting in the description of 12 new species and four new combinations based on historic names. Even though molecular phylogenetic analyses strongly support the segregation of these species, and are in agreement with previous studies, individual diagnostic morphological characters for each species could not be identified. However, discrete morphological traits corresponding to each of the three main groups of species were discovered. Lineages could be differentiated based on the average values of morphological traits as well as the presence/absence of characteristic asexual propagules and colony growth at 30C. Descriptions, illustrations are provided for the recognized species.